Thank you for the help

So I'm kind of a noob, I've leveled up to 70 on my sith assassin because when I tried to go through the portal of "Temple of Sacrifice" it said I had to be level 70+ or at least item level 210. Now that I am level 70 I try to go into the orange portal and it gives me an error message "Must be in ops group" So I figured I need to queue for it in the activity section. I go into that tab and I don't want to queue randomly for other ops so I unselect the other ops because I only want to queue for "Temple of Sacrifice"... The problem here is... I don't have the option to select "Temple of Sacrifice". I've looked around on the internet and nothing I found helps. What am I missing out on here?